SRI International has completed the second quarter of a program to develop field-emitter arrays for vacuum microelectronics. The goals of the effort are 5mA total current at 5 A/cm2 for at least 1 hour, and demonstrated modulation of the emission at 1 GHz. Improved vendor deposition of the oxide layer indicated that a cathode achieving 1000 A/cm2 shows very brittle oxide that tends to break up and flake off under the pressure of the contact leads. Low-capacitance cathode fabrication studies were temporarily discontinued after equipment failure. To date, 1000-tip cathodes have been operated with carefully processed, closed-spaced nickel anodes, presently at 15 mA and 22.8 A/cm2, for over 2700 hours. Major effort was directed toward detailed design of the apparatus required for microwave measurements, and on developing technologies for assembling microstrip lines and lead bonding them to SMA coaxial connectors and cathode arrays.

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